If you are in search of high quality permanent mold casting service, allow CFS Foundry to help you regardless of your industry. As the name suggests, this method offers superior accuracy and smooth surface finish, making it an excellent solution for the production of intricate cast aluminum parts.
What Is Permanent Mold Casting?
Sometimes the permanent mold casting process is also known as gravity die casting. This is a process of aluminum casting using reusable iron and steel molds. Sometimes we use permanent mold casting to replace high-pressure die casting and sand casting. Likewise, high pressure die casting, gravity die casting uses a reusable steel mold instead of a one-time use sand mold, and sand cores can be used to create internal voids and undercuts.
Permanent mold casting is preferred for producing large quantities of small and simple metal parts. It also provides uniform wall thicknesses. Non-ferrous metals are generally used in this process. These include aluminum alloys, magnesium alloys, and copper alloys. However, graphite molds can also be used to cast steels and irons. Permanent mold parts that are commonly made from this process include gears and gear housings, pipe fittings, valve bodies, pump components, electronic housings, manifolds, marine hardware, etc.
Below are the steps used in the permanent mold casting process:
- Mold Preparation: First, we make sure the mold is preheated to approximately 300-500°F (150-260°C). This allows for a better flow of the metal while reducing defects. Then, the mold cavity is surrounded with a ceramic coating to improve part removal and increase mold life.
- Assembling the Mold – The mold usually comprises two parts: the two halves of the mold and the cores, which are used to form complex features. These cores are usually made of iron or steel. However, sometimes expendable sand cores are used. This step involves inserting the cores into the mold halves. They are then clamped together.
- Pouring: The pouring is done slowly from a ladle into the mold. Molten metal is poured through a sprue at the top of the mold. The metal enters the mold cavity through a channel system.
- Cooling: After the molten metal is poured, it cools and solidifies in the mold.
- Opening the mold – once the metal has solidified, the mold halves are opened, and the casting is removed.
- Trimming: Some excess metal in the sprue and gating system remains attached to the solidified casting as it cools. Now, this excess material is trimmed away.
Permanent Mold Casting Advantages & Disadvantages
Permanent mold casting offers the following advantages for a suitable casting process to cast your design:
Strength
Permanent mold casting produces high-strength products that have 15% higher mechanical properties due to the lower grain structure created by the freezing rate of steel compared to sand. Many OEMs are taking advantage of the strength of permanent mold casting to switch from iron or steel castings to lighter aluminum permanent mold castings.
Surface Finish
The process provides a more refined and smoother surface finish than sand casting because a reusable steel or iron mold is used.
Dimensional Accuracy
For the production of optical and dimensional parts, permanent die casting is the best process after die casting.
However, the process also has some disadvantages, as it involves higher costs for producing the metal molds. Also, only non-ferrous metals are used due to their low melting point unless a particular graphite mold is made. In addition, the molds have a short shelf life due to thermal fatigue and erosion.
Permanent Mold Casting vs. Sand Casting: Which Should You Choose?
Permanent mold casting is basically an aluminum casting process. The process include molds made from iron and steel. Sometimes we use permanent mold casting to replace high-pressure die casting and sand casting. Likewise, high pressure die casting, permanent mold casting uses a reusable steel mold instead of a one-time use sand mold, and sand cores can be used to create internal voids and undercuts.
This process is best suited for medium to higher volumes when the part configuration dictates this type of casting or the process is best suited for the casting application. In most cases, the molds are fully CNC machined with the parting surfaces aligned with a locking system that provides excellent repeatable casting dimensional conditions. Compared to sand casting, permanent mold casting offers a better surface finish, fewer machining allowances required, and a deeper net shape profile due to the metal mold configurations. In addition, permanent mold casting is limited in size compared to sand casting. Also, tooling is more expensive than sand casting (although part prices tend to be lower!).
Why Choose CFS’ Permanent Mold Casting Services?
With years of experience, CFS Foundry prides itself on delivering the best quality. We ensure that each customer receives the following benefits when working with CFS on specific processes.
- Specialized permanent mold casting equipment
- Reliable quality assurance
- Small series or large series production
We use semi-automatic machines, which are different from traditional working methods. These machines allow us to produce larger quantities of castings with higher quality and short lead times, which ultimately shortens the time frame to completion.
For some unique designs, we use sand cores, which are used during the permanent mold casting process. We have the most advanced sand core production equipment that casts the molten metal without air bubbles, minimizing the risk of defects, followed by a thorough quality assurance process.
Before we start production, we discuss with our clients and pay attention to every little detail, including optimizing design, material selection, strength, size accuracy, and surface finish.
Our Permanent Mold Casting Capabilities:
- A356 Cast Aluminum Alloy: Many industries use permanent molds to cast Aluminum in steel and iron. However, many permanent mold castings are made of A356 Aluminum alloys. A356 aluminum alloy is comprised of 92.05% Aluminum, 7% Silicon, 0.35% Magnesium, 0.20% Iron, 0.20% Copper, 0.10% Maganese and 0.10% Zinc. CFS permanent mold casting produces A356 aluminum castings that are lightweight and extremely corrosion-resistant, like stainless steel.
- Sizes and Tolerances Range: We can produce aluminum casting with permanent mold casting ranging from 0.02kg to 30kgs. General casting tolerance ISO 8062 CT8 level can be guaranteed.
- T6 heat Treatment: To improve the permanent mold cast’s strength, we use in-house T6 heat treatment.
- Multiple Surface Finishes: Apart from shot blasting, we also offer other surface finishing to meet the need of clients with different surface finishing requirements. These include powder coating, polishing, anodization, etc.